“Dorothea Lange: Photography as Activism” at the Oakland Museum of California showcases the work of a photographer of peerless caliber, craft and artistry. The exhibition curates 47 works from her oeuvre that pay tribute to a woman who, in her quest to uproot social inequities by documenting them, examined much more than her famed Dust Bowl subjects. Visitors appreciate this tender attention to America’s underclasses and learn about a woman who devoted her professional life to capturing them on film.